Dynamometer type electric machine



Feb. 23, 1943- T. OKAMURA ET AL DYNAMOMETER TYPE ELECTRIC MACHINE Filed Oct. 3, 1941 Tadao @kamura, Kazuma Sakai, by fi amyfdw Their Attorney.

Patented Feb. 23, 1943 DYNAMOMETER TYPE ELECTRIC MACHINE Tadao Okamura, Tokyo, and, Kazuma Sakai,

Yokohama, Japan, assignors to General Electric Company, a corporation of New York Application October 3, 1941, Serial No. 413,412 In Japan August 23, 1940 '7 Claims.

Our invention relates to improvements in dynamo-electric machines and particularly to ventilating systems for machines wherein both of the relatively rotatable members are rotatably mounted.

In dynamo-electric machines having two relatively rotatable members, such as electric dynamometers, it is desirable to have the torque of the outer member substantially equal to the torque applied to the inner rotatable member. When a ventilating medium impeller is mounted on the shaft of the inner rotatable member for forcing ventilating air through the machine, a certain amount of the torque applied to this rotatable member is utilized in driving the impeller and no counterpart of this torque is produced in the outer relatively rotatable member. In electric dynamometers, a torque-measuring or indicating device usually is applied to the outer member, and if the torque in this outer member is less than the input of the inner memher, the measurement of the input torque is not accurate.

An object of our invention is to provide a dynamo-electric machine wherein both of the relatively rotatable members are movably mounted and a ventilating system is provided which does not interfere substantially with the sensitivity or the operation of the machine.

. Another object of our invention is to provide a torque-measuring device provided with a ventilating impeller driven by the device which will have substantially no effect on the accuracy of the measurement of the input torque of the machine.

Further objects and advantages of our invention will become apparent and our invention will be better understood from the following description referring to the accompanying drawing, and the features of novelty which characterize our invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In the drawing, Fig. l is a side elevational view of a cradled dynamometer provided with an embodiment of our improved ventilating system with a sectional view of the ventilating medium impeller and cooperating casing member; and Fig. 2 is a sectional end view taken along line 2-2 of Fig. 1.

Referring to the drawing, we have illustrated a dynamo-electric machine arranged to be operated as a dynamometer and including a rotatable member or armature it) provided with a commutator II and brushes l2. The armature is mounted on a shaft I3 which is rotatably supported in bearings arranged in upright pedestal arms I4 and 15 mounted on a base IS. A field member including a frame I"! is arranged to cooperate electrodynamically with the armature HI and also is rotatably or movably supported in bearings mounted in the pedestal arms 14 and it of the mounting base l6. Rotational movement of the field frame structure I! is limited by a lug l8 secured to an end shield [Son one end of the field frame structure. The lug i8 extends between two limit stops 26 secured to the vertically extending pedestal arm I5 of the mounting base.

A dynamometer lever arm 2i is secured to a mounting plate 22 to one side of the field frame structure ii and a reverse torque mechanism connects the outer end of the lever arm 21 to a force-measuring device. This reverse torque mechanism includes a bar Z3 secured to the end of the lever arm 2|, and each of the ends of the bar 23 is provided with a notch arranged to engage with pivot pins 24 and 25, of the reverse torque mechanism. If the torque on the field frame H is in a clockwise direction, as viewed in Fig. 2, the notch in the bar 23 engaging pin 24 will exert a downward pull on a link 26 which is connected at 2'! to a spring balance scale 28 and to a balance mechanism 29. The balance mechanism is pivotally suspended at 30 from a supporting bar 3| mounted upon vertical supports 32 which are secured to the mounting base I6. If the torque on the field frame structure H is in a counterclockwise direction, as viewed in Fig. 2, the notch in the bar 23 adjacent the pin 24 will become d sengaged from this pin and the notch at the other end of the bar 23 will press upwardly against the pin 25 and exert an upward force on a connecting link 33. The lower end of the link 33 will engage a pin 34 secured to one end of a bar 3'5 pivotally supported at 36 on an adjustable mounting rod 31 secured to the mounting base it. The upward force transmitted to the link 33 by the bar 23 will be transmitted through the pivoted bar 35, and a corresponding downward force will be exerted by a pin 38 secured to the other end of the bar 35. The pin 38 will engage the lower portion of a lost-motion slot 39 formed in the link 26 and will exert a downward pull on the spring scale 28 and the balance mechanism 29. In this manner, both counterclockwise and clockwise torques will give positive indications on the force-measuring device including the spring scale 28 and the balance mechanism 29.

In order to provide for the proper ventilation of the dynamo-electric machine, ventilating openings 49 are formed in one end of the field frame l1, and a ventilating medium impeller having impeller blades 4| is secured to a mounting ring 42 supported on the end of the armature shaft I3 opposite the openings 40 and is arranged to be driven with the rotatable member of the machine. The operation of the impeller absorbs a certain amount of the input to the rotatable member it which does not appear as an electrodynamic component of counter-torque on the field frame member ll. This would cause errors in the torque measurements indicated by the scale 28 and the balance 29. In order to correct such discrepancies, a cooperating impeller casing 43 is arranged about the impeller and is secured to an end shield 44 as a part of the field frame member IT. This impeller casing 43 is provided with a plurality of vanes 45 which is arranged to exhaust Ventilating medium radially out of the casing by redirecting the air expelled by the impeller, thereby absorbing the rotational component of energy in the ventilating medium and providing a torque on the field frame member ll substantially equal to the input torque to the impeller. These vanes are arranged'in two sections in the impeller casing 43, such that operation of the rotatable member in in either direction will cause the rotational energy of the ventilating medium to be absorbed by the vanes 45. The direction of flow of ventilating medium for clockwise and counter-clockwise rotation of the rotatable member 10 is indicated by arrows in Fig. 2. In this manner, a torque is provided on the field frame member H which is substantially equal to the input torque to the impeller, and the counter-torque indicated by the scale 28 and the balance arm 29 is equal to the total in the appended claims to cover all modifications which do not depart from the spirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

- 1. A dynamo-electric machine having a rotatable member, a second member movably mounted about said rotatable member and arranged to cooperate electro-dynamically there- 'with, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, and means including a cooperating impeller casing arranged to exhaust ventilating medium radially out of said dynamo-electric machine for providing a torque on said second member substantially:

equal to the input torque to said impeller.

2. A dynamo-electric machine having a rotatable member, a second member movably mounted about said rotatable member and arranged to cooperate electro-dynamically therewith, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, and means for absorbing rotational energy in said ventilating medium exhausted by said impeller for providing a torque on said second member substantially equal to the input torque to said impeller.

3. A dynamo-electric machine having a rotatable member, a second member movably mounted about said rotatable member and arranged to cooperate electro-dynamically therewith, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, and means including a. cooperating impeller casing arranged to exhaust ventilating medium out of said dynamo-electric machine for absorbing rotational energy in ventilating medium exhausted by said impeller for providing a torque on said second member substantially equal to the input torque to said impeller.

4. A dynamo-electric machine having a rotatable member, a second member movably mounted about said rotatable member and arranged to cooperate electro-dynamically therewith, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, and means including a cooperating impeller casing as a part of said second member and having vanes arranged to absorb rotational energy in the ventilating medium exhausted by said impeller for providing a torque on said second member substantially equal to the input torque to said impeller.

5. A dynamo-electric machine having a rotatable member, a second member movably mounted about said rotatable member and arranged to cooperate electro-dynamically therewith, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, and means including a cooperating impeller casing as a part of said second member and having vanes arranged to exhaust ventilating medium radially out of said dynamo-electric machine for absorbing rotational energy in ventilating medium exhaustsed by said impeller for providing a torque on said second member substantially equal to the input torque to said impeller.

6. A torque measuring device having a dynamo-electric machine rotatable member, a second member mounted for limited rotational movement about said rotatable member and arranged to cooperate electro-dynamically therewith, a ventilating medium impeller arranged to be driven with said rotatable member for cooling said dynamo-electric machine, means including a cooperating impeller casing arranged to exhaust ventilating medium radially out of said second member for providing a torque on said second member substantially equal to the input torque to said impeller, and means for indicating the total torque reaction on said second member.

7. A torque measuring device having a dynamo-electric machine rotatable member, a sec- I the input torque to said impeller for either direction of rotation, and means for indicating the total torque reaction on said second member.

TADAO OKAMURA. KAZUMA SAKAI. 

